Swift-单元格展开收起

UITableViewCell单元格点击收起比较常见，简单的看一下效果图:

FlyElephant_Cell.gif

通过Section的状态来来控制Section中的Cell的高度来实现，Section的Model定义如下:
<pre><code>`struct ExpandSection {
var title:String!
var items:[String]!
var expanded:Bool

init(title:String,items:[String],expanded:Bool = true) {
    self.title = title
    self.items = items
    self.expanded = expanded
}

}</code></pre> 数据初始化: <pre><code> tableView = UITableView(frame: CGRect.init(x: 0, y: 64, width:self.view.bounds.width, height: self.view.bounds.height - 64), style: .plain)
tableView?.register(UITableViewCell.classForCoder(), forCellReuseIdentifier: "UITableViewCell")
tableView?.delegate = self
tableView?.dataSource = self

    self.view.addSubview(tableView!)
    
    sections = [
        ExpandSection(title: "简书", items: ["FlyElephant", "keso"]),
        ExpandSection(title: "编程语言", items: ["Swift", "Objective-C", "JavaScript", "Python"]),
        ExpandSection(title: "地区", items: ["北京", "河南", "江西"]),
    ]`</code></pre>

UITableView实现:
<pre><code>` func numberOfSections(in tableView: UITableView) -> Int {
return sections.count
}

func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return self.sections[section].items.count
}

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let tableViewCell:UITableViewCell = tableView.dequeueReusableCell(withIdentifier: "UITableViewCell")! as UITableViewCell 
    var content:String = ""
    if sections[indexPath.section].expanded {
        content = sections[indexPath.section].items[indexPath.row]
    }
    tableViewCell.textLabel?.text = content
    
    return tableViewCell
}

func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
    let view:UIView = UIView.init(frame: CGRect.init(x: 0, y: 0, width: tableView.bounds.width, height: 44.0))
    view.backgroundColor =  UIColor(hex: 0x2E3944)
    
    let textlabel:UILabel = UILabel.init(frame: CGRect.init(x: 10, y: 0, width: view.bounds.width, height: 44.0))
    textlabel.text = sections[section].title
    textlabel.textColor = UIColor.white
    textlabel.font = UIFont.systemFont(ofSize: 15.0)
    view.addSubview(textlabel)
    
    let tapGesture:UITapGestureRecognizer = UITapGestureRecognizer.init(target: self, action: #selector(tapSectionHeader(sender:)))
    view.tag = section
    view.addGestureRecognizer(tapGesture)
    
    return view
}

func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
    return 44.0
}

func tableView(_ tableView: UITableView, heightForFooterInSection section: Int) -> CGFloat {
    return 0.0
}

func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
    return sections[indexPath.section].expanded ? 44 : 0
}`</code></pre>

SectionHeader点击事件:
<pre><code>` func tapSectionHeader(sender:UITapGestureRecognizer) {
let section:Int = (sender.view?.tag)!
sections[section].expanded = !sections[section].expanded

    for i in 0..<sections[section].items.count {
        tableView?.reloadRows(at: [IndexPath(row: i, section: section)], with: .automatic)
    }
}`</code></pre>